Waves that have a constant amplitude throughout their propagation are called non-dispersive waves. Non-dispersive waves maintain their shape and amplitude as they travel through a medium. This means that regardless of the distance traveled, the amplitude of the wave remains the same.
One example of a non-dispersive wave is a pure sine wave with a single frequency. In an idealized scenario without any external factors affecting the wave, such as damping or interference, a sine wave will propagate with a constant amplitude.
However, it's important to note that in real-world situations, many waves experience some degree of dispersion or attenuation over long distances or due to interactions with the environment. These factors can cause the amplitude of the wave to change over time or space. Examples of dispersive waves include water waves and electromagnetic waves in certain materials.
To summarize, non-dispersive waves, such as idealized sine waves, have a constant amplitude throughout their propagation in the absence of any external influences.